gems, gems general

Sterrett’s annual review surveys gem mining and production in the United States during 1912, with detailed descriptions of important deposits, their geology, mining, gem quality, and commercial prospects. Montana sapphire was the principal domestic gem mineral, with blue stones from Fergus County and varicolored material from placer deposits. Particular attention is given to the newly developed precious-opal deposits of Virgin Valley, Humboldt County, Nevada, where brilliant opal occurs commonly in association with petrified wood, and to extensive investigations of amethyst and beryl occurrences in North Carolina and Virginia. The report also discusses emerald mining at the Old Plantation mine near Shelby, North Carolina; Arkansas and other American diamond occurrences; chrysoprase, amazon stone, topaz, tourmaline, turquoise, variscite, and related gem materials. Domestic production was valued at $319,722, a decrease of $23,970 from 1911; opal and kunzite increased markedly, whereas turquoise, chrysoprase, and emerald declined. Sterrett additionally records the American jewelry trade’s decision to adopt the 200-milligram metric carat from July 1913 and the 1912 standardized list of birthstones adopted by the American National Retail Jewelers’ Association.